1256205517440 has 64 divisors (see below), whose sum is σ = 4004155092960. Its totient is φ = 334988137472.

The previous prime is 1256205517423. The next prime is 1256205517487. The reversal of 1256205517440 is 447155026521.

It is a tau number, because it is divible by the number of its divisors (64).

It is a junction number, because it is equal to n+sod(n) for n = 1256205517392 and 1256205517401.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 327134934 + ... + 327138773.

Almost surely, 2^{1256205517440} is an apocalyptic number.

1256205517440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1256205517440 is an abundant number, since it is smaller than the sum of its proper divisors (2747949575520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1256205517440 is an equidigital number, since it uses as much as digits as its factorization.

1256205517440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 654273729 (or 654273717 counting only the distinct ones).

The product of its (nonzero) digits is 336000, while the sum is 42.

The spelling of 1256205517440 in words is "one trillion, two hundred fifty-six billion, two hundred five million, five hundred seventeen thousand, four hundred forty".